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Lice can be the cause of white plaque on cacti
White coating on cacti - What to do?
If a white surface spreads on cacti, optics and vitality are affected equally. The two most common causes of the problem can be found here. Use our tips for effective control by natural means.
Cause # 1: Mildew
Powdery, white coating on the green epidermis indicates the fungal infection powdery mildew. As the disease progresses, the infected parts of the plant turn brown and die. How to act right now:
For cacti in the greenhouse you get help from the animal kingdom. Mushroom ladybirds (Psyllobora vigintiduopunctata), sixteen-spotted ladybirds (Halyzia sedecimguttata) as well as squirrel flies (Myathropa florea) graze the mushroom grass with enthusiasm.
Cause # 2: Woll lice
If the pad reminds of small, white cotton balls, you are confronted with a pest infestation. These are 1-5 mm small lice and their larvae. The parasites protect themselves with a waxy shell and absorb the sap. Upon contact, a greasy, white plaque is formed, so that the pests are also referred to as lice. This is how you proceed against the plague:
The use of beneficial organisms has also proven itself in the fight against mealybugs. This is especially true for locations such as the greenhouse, greenhouse or conservatory. The Australian ladybird (Cryptolaemus montrouzieri) has the lice at the top of a diet. In special farms, the beneficials are bred and can be purchased there.
Tips
If the topping on cacti is more greyish than white, you are dealing with gray mold (Borytis). This fungal infection often occurs on desert cacti, which are placed in a humid location. In the early stages, an immediate change of location to a sunny, air-dry place can help. Otherwise, you can not avoid disposing of the affected cactus.